Belt tensioner, part therefor and methods of making the same

ABSTRACT

A tensioner for a power transmission belt that is adapted to be operated in an endless path and comprising a support unit for being fixed relative to the belt, a belt engaging unit carried by the support unit and being movable relative thereto, a mechanical spring unit operatively associated with the support unit and the belt engaging unit for urging the belt engaging unit relative to the support unit and against the belt with a force to tension the belt, and a fluid dampening unit operatively associated with the support unit and the belt engaging unit to dampen the movement of the belt engaging unit relative to the support unit in at least one direction of movement thereof, the fluid dampening unit comprising a piston and cylinder unit. The mechanical spring unit comprises a pair of coiled compression springs with their longitudinal axes disposed in substantially parallel side-by-side spaced relation. The fluid dampening unit is generally disposed between the springs and in substantially parallel relation therewith. The belt engaging unit and the support unit have a tongue and groove arrangement for providing sliding movement therebetween.

CROSS REFERENCE TO RELATED APPLICATION

This application is a continuation-in-part patent application of its copending parent patent application, Ser. No. 301,351, filed Sept. 11, 1981.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to an improved tensioner for an endless power transmission belt or the like, an improved part for such a tensioner or the like and to methods of making such a tensioner and/or part therefor.

2. Prior Art Statement

It is known to applicant to provide a tensioner for a power transmission belt that is adapted to be operated in an endless path, the tensioner comprising a support means for being fixed relative to the belt, a belt engaging means carried by the support means and being movable relative thereto, mechanical spring means operatively associated with the support means and the belt engaging means for urging the belt engaging means relative to the support means and against the belt with a force to tension the belt, and a fluid dampening means operatively associated with the support means and the belt engaging means to dampen the movement of the belt engaging means relative to the support means in at least one direction of movement thereof, the fluid dampening means comprising a piston and cylinder means.

For example, see the copending patent application Ser. No. 296,694, filed Aug. 27, 1981 of Leslie B. Wilson, wherein the fluid dampening means comprises a cylinder means having a piston means therein and defining two chambers for fluid in the cylinder means on opposite sides of the piston means together with preferential flow control means interconnecting the two chambers together.

Also see the copending patent application Ser. No. 296,697, filed Aug. 27, 1981 of Randy C. Foster et al wherein another such tensioner is provided and the fluid dampening means thereof comprises a cylinder means having a piston means therein and defining two chambers for fluid in the cylinder means on opposite sides of the piston means with the sring means being disposed in one of those chambers.

It is also known to provide a belt tensioner with a friction surface dampening means of the solid type utilized to tend to dampen vibrations and the like that are imposed on the belt tensioner.

It is also known to provide fluid couplings, such as torque converters, wherein rotational movement of one member causes rotational movement of another member because a fluid translates such movement between the two members, each member having vanes thereon.

SUMMARY OF THE INVENTION

It is one feature of this invention to provide an improved tensioner for a power transmission belt or the like.

In particular, it was found according to the teachings of the invention in the copending parent patent application, Ser. No. 301,351, filed Nov. 11, 1981, that a relatively small and compact belt tensioner could be provided by uniquely arranging the mechanical spring means thereof and the fluid dampening means thereof in a manner believed to be more compact than the arrangements set forth in the aforementioned copending patent applications, Ser. No. 296,697, filed Aug. 27, 1981, of Leslie B. Wilson and Ser. No. 296,697, filed Aug. 27, 1981, of Randy C. Foster et al, both of these copending patent applications being hereby incorporated into this disclosure by this reference thereto.

In particular, it was found according to the teachings of that invention that the spring means of a belt tensioner can comprise a pair of springs disposed in substantially parallel spaced relation with the fluid dampening means having at least a part thereof disposed between the springs in substantially parallel relation therewith to render the belt tensioner substantially small and compact.

For example, one embodiment of that invention provides a tensioner for a power transmission belt that is adapted to be operated in an endless path, the tensioner comprising a support means for being fixed relative to the belt, a belt engaging means carried by the support means and being movable relative thereto, mechanical spring means operatively associated with the support means and the belt engaging means for urging the belt engaging means relative to the support means and against the bet with a force to tension the belt, and a fluid dampening means operatively associated with the support means and the belt engaging means to dampen the movement of the belt engaging means relative to the support means in at least one direction of movement thereof, the mechanical spring means comprising a pair of spring disposed in substantially parallel spaced relation with the fluid dampening means having at least a part thereof disposed between the springs and in substantially parallel relation therewith.

It is another feature of that invention to provide an improved fluid dampening means for a belt tensioner or the like.

In particular, it was found according to the teachings of that invention that the fluid dampening means for a belt tensioner could comprise a rotary dampening means.

For example, another embodiment of that invention provides a tensioner for a power transmission belt that is adapted to be operated in an endless path, the tensioner comprising a support means for being fixed relative to the belt, a belt engaging means carried by the support means and being movable relative thereto, mechanical spring means operatively associated with the support means and the belt engaging means for urging the belt engaging means relative to the support means and against the belt with a force to tension the belt, and a fluid dampening means operatively associated with the support means and the belt engaging means to dampen the movement of the belt engaging means relative to the support means in at least one direction of movement thereof, the fluid dampening means comprising a rotary dampening means.

It is another feature of that invention to provide an improved part for such a tensioner, the improved part being the rotary dampening means previously described.

However, it is believed that such improved rotary dampening means or device can be utilized for other purposes than for a belt tensioner and therefore that invention is not to be limited to a rotary dampening means only for a belt tensioner.

For example, another embodiment of that invention provides a fluid dampening device comprising a first member, and a second member disposed in the first member with the members being arranged for relative movement therebetween and cooperating together so that a fluid therein will tend to dampen such movement in at least one direction, one of the members being rotatably mounted relative to the other of the members whereby the fluid dampening device is a rotary dampening device.

It was found according to the teachings of this invention that the previously described tensioner could have a tongue and groove arrangement for providing sliding movement between the belt engaging means and the support means thereof.

For example, one embodiment of this invention provides a tensioner for a power transmission belt that is adapted to be operated in an endless path, the tensioner comprising a support means for being fixed relative to the belt, a belt engaging means carried by the support means and being movable relative thereto, mechanical spring means operatively associated with the support means and the belt engaging means for urging the belt engaging means relative to the support means and against the belt with a force to tension the belt, and fluid dampening means operatively associated with the support means and the belt engaging means to dampen the movement of the belt engaging means relative to the support means in at least one direction of movement thereof, the fluid dampening means comprising a piston and cylinder means and the mechanical spring means comprising a pair of coiled compression springs with their longitudinal axes disposed in substantially parallel side-by-side spaced relation. The fluid dampening means is generally disposed between the springs and in substantially parallel relation therewith. The belt engaging means and the support means have a tongue and groove means for providing for sliding movement therebetween.

It was also found according to the teachings of this invention that the fluid dampening means for any of the previously described tensioners could have part of the cylinder member thereof formed from a one-piece elongated cup-shaped member.

For example, another embodiment of this invention provides a tensioner for a power transmission belt that is adapted to be operated in an endless path, the tensioner comprising a support means for being fixed relative to the belt, a belt engaging means carried by the support means and being movable relative thereto, a mechanical spring means operatively associated with the support means and the belt engaging means for urging the belt engaging means relative to the support means and against the belt with a force to tension the belt, and fluid dampening means operatively associated with the support means and the belt engaging means to dampen the movement of the belt engaging means relative to the support means in at least one direction of movement thereof, the mechanical spring means comprising a pair of springs disposed in substantially parallel spaced relation. The fluid dampening means has at least a part thereof disposed between the springs and in substantially parallel relation therewith. The fluid dampening means comprises a piston and cylinder means, the piston and cylinder means comprising a cylinder member and a piston member disposed in the cylinder member. One of the members is operatively interconnected to the support means and the other of the members is operatively interconnected to the belt engaging means whereby the members are arranged for relative movement therebetween. The cylinder member comprises a one-piece elongated cup-shaped member having a closed end and an open end, the cylinder member further comprising a cap means closing the open end of the elongated cup-shaped member and having an opening therethrough. The piston member has a piston rod that projects through the opening of the cap means.

Accordingly, it is an object of this invention to provide an improved tensioner for a power transmission belt or the like that is adapted to be operated in an endless path, the tensioner of this invention having one or more of the novel features of this invention as set forth above or hereinafter shown or described.

Other objects, uses and advantages of this invention are apparent from a reading of this description which proceeds with reference to the accompanying drawings forming a part thereof and wherein:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a fragmentary isometric view looking toward the front end of an automobile engine which utilizes one embodiment of the belt tensioner of this invention.

FIG. 2 is a view looking perpendicularly toward the front end of the automobile engine of FIG. 1.

FIG. 3 is an enlarged front view, partially broken away and partially in cross section, of the belt tensioner of this invention that is being utilized for tensioning the power transmission belt of FIGS. 1 and 2.

FIG. 4 is a cross-sectional view taken on lines 4--4 of FIG. 3.

FIG. 5 is a cross-sectional view taken on lines 5--5 of FIG. 3.

FIG. 6 is an exploded perspective view of the various parts forming the belt tensioner of FIGS. 3-5.

FIG. 7 is a schematic view in cross section and illustrates the fluid flow control means of the fluid dampening means of the belt tensioner of FIGS. 3-6.

FIG. 8 is a view similar to FIG. 3 and illustrates another embodiment of the belt tensioner of this invention.

FIG. 9 is a view similar to FIG. 8 and illustrates another embodiment of the belt tensioner of this invention.

FIG. 10 is a side view of the belt tensioner of FIG. 9 and is taken in the direction of the arrows 10--10 thereof.

FIG. 11 is a cross-sectional view of the fluid dampening means of the belt tensioner of FIGS. 9 and 10 and is taken on lines 11--11 of FIG. 10.

FIG. 12 is an exploded perspective view illustrating the parts of the fluid dampening means of the belt tensioner of FIGS. 9 and 10.

FIG. 13 is a view similar to FIG. 1 and is thereby a fragmentary isometric view looking toward the front end of an automobile engine which utilizes another embodiment of the belt tensioner of this invention.

FIG. 14 is a view looking perpendicularly toward the front end of the automobile engine of FIG. 13.

FIG. 15 is an enlarged front view of the belt tensioner of this invention that is being utilized for tensioning the power transmission belt of FIGS. 13 and 14.

FIG. 16 is a side view of the belt tensioner of FIG. 15 and is taken in the direction of the arrows 16--16 of FIG. 15.

FIG. 17 is a bottom view of the belt tensioner of FIG. 15 and is taken in the direction of the arrows 17--17 of FIG. 15.

FIG. 18 is a top view of the tensioner of FIG. 15 and is taken in the direction of the arrows 18--18 of FIG. 15.

FIG. 19 is a fragmentary cross-sectional view taken on line 19--19 of FIG. 16.

FIG. 20 is an enlarged fragmentary cross-sectional view of the fluid dampening means of the belt tensioner of FIGS. 15-19 and 21.

FIG. 21 is an exploded isometric view of the various parts of the belt tensioner of FIG. 15.

FIG. 22 is a reduced fragmentary view similar to FIG. 20 and illustrates another embodiment of the fluid dampening means of this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

While the various features of this invention are hereinafter illustrated and described as providing a belt tensioner for a particular power transmission belt of a particular motor vehicle engine, it is to be understood that the various features of this invention can be utilized singly or in any combination thereof to provide a belt tensioner for other arrangements as desired.

Also, while the improved rotary dampening means of this invention is described and illustrated as providing part of a belt tensioner, it is to be understood that the improved rotary dampening means of this invention can be utilized for other purposes as desired.

Therefore, this invention is not to be limited to only the embodiments illustrated in the drawings, because the drawings are merely utilized to illustrate one of the wide variety of uses of this invention.

Referring now to FIGS. 1 and 2, an automobile engine is generally indicated by the reference numeral 20 and utilizes an endless power transmission belt 21 for driving a plurality of driven accessories as hereinafter set forth, the improved belt tensioner of this invention being generally indicated by the reference numeral 22 and being utilized to provide a tensioning force on the belt 21 in a manner hereinafter set forth.

The endless power transmission belt 21 may be of any suitable type known in the art and is preferably made primarily of a polymeric material because the unique features of the tensioner 22 of this invention readily permits the tensioner 21 to tension a belt having a polyeser load-carrying cord in an efficient manner as hereinafter described.

The belt 21 is driven by a driving sheave 23 which is operatively interconnected to the crankshaft of the engine 20 in a manner well known in the art. The driving sheave 23 drives the belt 21 in an endless path and thereby drives a sheave 24 of a power steering device used in an automobile (not shown) utilizing the engine 20, a sheave 25 of an engine water pump, a sheave 26 of an air pump of a type used in an antipollution system for the engine 20, a sheave 27 of an engine electrical alternator 28, and a sheave 30 of a compressor 31 of an air conditioning system for the automobile utilizing the engine 20.

All of the driven accessories, through their sheaves 24, 25, 26, 27 and 30, impose a load on the belt 21. However, only the detailed description of the load being imposed by the compressor 31 and its sheave 30 on the belt 21 will be hereinafter described inasmuch as such load is generally of a comparatively high magnitude.

In particular, the compressor 31, upon being driven, creates a slack side 33 and a tight side 34 in the belt 21 upon turning on of the air conditioner system in the automobile, the slack side 33 and tight side 34 being produced since the belt is rotating clockwise as indicated by the arrow 35 in FIGS. 1 and 2.

The belt tight side 34 (and hence, slack side 33) varies in tightness, i.e., magnitude of tightness, in a cyclic manner and as a function of the inherent cyclic change in the loads imposed by the air compressor 31. This cyclic change and load varies between greater extremes in applications where the compressor 31 is of a piston type. The cyclic load imposed by the compressor 31 has a tendency to cause the slack side 33 of the belt 21 to vibrate or oscillate.

In addition to such vibrations and oscillations of the belt 21, it is known that normal belt wear and heat variations in the engine compartment for the engine 20 produce variations in the length of the belt 21 that require compensation for the same.

Thus, it is known that it is difficult to maintain such a belt 21 under tension with a force required to insure non-slipping engagement and driving of the driven sheaves whereby numerous belt tensioners have been proposed and used heretofore in an effort to provide the required tension.

It is believed that the improved belt tensioner 22 of this invention functions in a manner to provide a proper tensioning force on the belt 21 to overcome the aforementioned problems, namely, provides the required tension in the overall belt 21 as well as prevents any tendency of the belt to oscillate in an undesirable manner as a result of the cyclic load change imposed by the compressor 31 whereby the improved belt tensioner 22 of this invention will now be described.

As best illustrated in FIGS. 3 and 6, the improved belt tensioner 22 of this invention comprises a support means 36 adapted to be fixed to a mounting bracket 37 of the engine 20 as illustrated in FIGS. 1 and 2. A belt engaging means that is generally indicated by the reference numeral 38 is movably carried by the support means 36 in a manner hereinafter set forth. The tensioner 22 has mechanical spring means that is generally indicated by the reference numeral 39 operatively associated with the support means 36 and belt engaging means 38 to tend to urge the belt engaging means 38 against the slack side 33 of the belt 21 in substantially a true vertically downwardly direction in a manner to substantially bisect the angle made by the belt 21 between the sheaves 27 and 30 as illustrated in FIG. 2.

The belt tensioner 22 also includes a fluid dampening means that is generally indicated by the reference numeral 40 and is operatively associated with the support means 36 and the belt engaging means 38 to dampen movement of the belt engaging means 38 relative to the support means 36 in a manner hereinafter set forth.

The belt engaging means 38 comprises an idler pulley 41 rotatably mounted on an axle 42 carried by a slide member 43 disposed for sliding in a box-like member 44 of the support means 36 in a manner hereinafter set forth, the slide member 43 having a substantially rectangular front wall 45 and a pair of rearwardly extending substantially parallel rectangular and integral side walls 46 and 47 being bridged by a transverse wall 48 secured thereto in any suitable manner, such as by welding or the like. In this manner, the rearwardly extending side walls 46 and 47 define a pair of outwardly facing substantially parallel surfaces 49 and 50 while the transverse wall 48 defines a surface 51 that is disposed between and transverse to the side surfaces 49 and 50 for a purpose hereinafter described.

The box-like member 44 of the support means 36 has a substantially rectangular rear wall 52 with a pair of forwardly extending parallel and integral side walls 53 and 54 which respectively define inwardly facing substantially parallel surfaces 55 and 56 for respectively facing the side surfaces 49 and 50 of the slide member 43 of the belt engaging means 38 for a purpose that will be apparent hereinafter.

A substantially rectangular bottom wall 57 is secured to the rear wall 52 and side walls 53 and 54 of the support member 44 in any suitable manner, such as by welding or the like, and a substantially rectangular top wall 58 is likewise secured to the rear wall 52 and side walls 53 in any suitable manner, such as by welding or the like. In addition a partial substantially rectangular front wall 59 and partial side walls 60 and 61 are carried by the top wall 58 and extend across and overlap the side walls 53 and 54 in a cap-like manner as illustrated in FIGS. 3 and 4 to provide a means for capturing and guiding up and down movement of a pair of substantially rectangular spring retainers 62 which respectively have threaded openings 64 passing therethrough and respectively threadedly receiving threaded adjusting members 65 that are rotatably carried in openings 66 in the top wall 58.

In particular, each threaded adjusting member 65 has a reduced non-threaded section 67 intermediate the threaded portion 68 thereof and an enlarged head 69 thereof that is telescopically received in an opening 66 of the top wall 58 and is held therein by a C-shaped clip 70 in a manner well known in the art so that rotation of the particular threaded fastening member 65, such as by turning the head 69 thereof with a suitable tool or the like, will cause rotation of the adjusting member 65 and, thus, a threading relation of its respective spring retainer 62 upwardly or downwardly on the threaded fastening member 65 within the top cap portion of the box-like support member 44 for a purpose hereinafter described.

The facing side surfaces 55 and 56 of the box-like support member 44 respectively are provided with a pair of parallel grooves 71 that respectively extend from openings 72 formed through the respective side wall 53 or 54 to the ends 73 thereof.

In a similar manner the outwardly facing side surfaces 49 and 50 of the slide member 43 of the belt engaging means 38 each has a pair of parallel grooves 74 formed therein with each groove 74 terminating at the opposed ends 75 and 76 thereof.

The grooves 74 of the slide member 43 cooperate with the grooves 71 of the support member 44 to carry bearing means that are generally indicated by the reference numeral 77 and that facilitate sliding movement of the slide member 43 relative to the support member 44.

In particular, the bearing means 77 comprise a plurality of ball bearings 78 that substantially fill the grooves 74 of the slide member 43 and partially fill the grooves 77 of the support member 44 to permit up and down sliding movement of the slide member 43 within the box-like member 44 as illustrated in FIGS. 3 and 4.

In order to initially dispose the ball bearings 78 in the cooperating grooves 71, 74, the slide member 43 is positioned in the member 44 so that the upper ends 75 of the grooves 74 are slightly above the openings 72 in the side walls 53 and 54 of the member 44 so that the ball bearings 78 can be fed through the openings 72 into the cooperating grooves 71 and 74. Once the grooves 74 have been filled with the ball bearings 78, the slide member 43 is moved downwardly so that the ends 75 of the grooves 74 are below the openings 72 whereby the ball bearings 78 cannot escape from the cooperating grooves 71, 74, the openings 72 being so positioned that the normal range of up and down movement of the slide member 43 relative to the box-like member 44 during its belt tensioning function of the tensioner 22 in a manner hereinafter set forth will not cause the upper ends 75 of the grooves 74 of the slide member 43 to reach the openings 72 whereby the ball bearings 78 are fully captured in the cooperating grooves 71 and 74 for their substantially frictionless bearing purpose.

The mechanical spring means 39 of the tensioner 22 of this invention comprises a pair of coiled compression springs 79 with their longitudinal axes disposed in spaced apart parallel side-by-side spaced relation in the box-like support member 44 and respectively have upper ends 80 bearing against the adjustable spring retainers 62 while having the lower ends 81 thereof respectively being received in substantially cylindrical recesses 82 formed in the surface 51 of the transverse wall 48 of the slide member 43.

In this manner, the force of the compression springs 79 tends to urge the slide member 43 downwardly relative to the support member 44, the force of the compression springs 79 being adapted to be adjusted by the adjustable spring retainer 62 being axially threaded upwardly and downwardly on the respective threaded adjusting members 65 in the manner previously set forth.

The fluid dampening means 40 comprises a piston and cylinder means that is generally indicated by the reference numeral 83 and comprises a cylinder member 84 and a piston member 85, FIG. 7, disposed for movement within a substantially cylindrical chamber 86 formed in the cylinder member 84, the piston member 85 having a piston rod 87 secured thereto and extending from opposed sides 88 and 89 thereof so that a lower part 90 of the piston rod 87 extends out of an opening 91 in an upper end wall 95 of the cylinder member 84.

The piston member 85 of the fluid dampening means 40 has an external peripheral surface 96 disposed in sliding and sealing engagement with the internal peripheral surface 97 of the cylinder member 84 that defines the chamber 86 thereof whereby the piston member 85 divides the chamber 86 into an upper chamber section 98 and a lower chamber section 99 substantially sealed from each other by the piston member 85. However, the chamber sections 98 and 99 are fluidly interconnected together by a passage defining means that is generally indicated by the reference numeral 100 and comprises a conduit means 101 having one end 102 thereof secured in an opening 103 formed through the cylinder member 84 adjacent the end wall 95 thereof while the other end 104 of the conduit means 101 is secured in an opening 105 formed through the cylinder member 84 adjacent the end wall 92, the conduit means 101 having a flow control valve means therein that is generally indicated by the reference numeral 106 and that is utilized for controlling fluid flow through the conduit means 101 in a manner hereinafter described.

The cylinder member 84 has a pair of opposed reduced ends 107 and 108 through which the piston rod parts 93 and 90 respectively extend, the reduced end 108 being externally threaded to be threadedly received in an internally threaded bore 109 of a substantially rectangular block 110 secured to the rear wall 52 of the support member 44 in any suitable manner, such as welding or the like, whereby the lower end 108 of the cylinder member 84 is secured to the support member 44 so as to be non-movable relative thereto. The upper end 107 of the cylinder member 84 projects out of an opening 111 formed in the top wall 58 of the box-like support member 44.

The piston member 85, in turn, is operatively interconnected to the slide member 43 because the lower piston rod part 90 thereof has a reduced externally threaded section 112 received through an opening 113 formed through the transverse wall 48 of the slide member 43 and carries a nut 114 thereon to sandwich the transverse wall 48 between the nut 114 and an annular shoulder 115 on the piston rod section 90 whereby the piston member 85 will move in unison with the slide member 43 relative to the support member 44 in a manner hereinafter set forth.

Thus, it can be seen that the piston and cylinder means 83 is disposed substantially parallel to the springs 79 and between the same, the springs 79 and piston member 85 being operatively interconnected to the slide member 43 and the springs 79 and cylinder member 84 being operatively interconnected to the support means 36 and thereby permit the tensioner 22 to be substantially small and compact to operate in a manner hereinafter set forth.

The flow control valve means 106 illustrated in FIG. 7 comprises a housing means 116 having a first passage 117 passing therethrough and defining opposed openings 118 and 119 in the housing means 116 that respectively receive ends 120 and 121 of conduit sections 122 and 123 of the conduit means 101 as illustrated, the conduit ends 120 and 121 being secured in the openings 118 and 119 in any suitable manner, such as by the threaded relation illustrated.

A one-way check valve means that is generally indicated by the reference numeral 124 in FIG. 7 is disposed in the first passage means 117 to permit fluid flow from the conduit section 123 to the conduit section 122 and, thus, from the chamber section 99 to the chamber section 98 of the fluid dampening means 40 while preventing reverse flow from the conduit section 122 to the conduit section 123 through the first passage 117 and, thus, from the chamber section 99 of the fluid dampening means 40.

In particular, the one-way check valve means 124 comprises a movable valve member 125 normally urged against a valve seat 126 in the passage means 117 by a compression spring 127 so that fluid pressure from the conduit section 123 will open the valve member 125 against the force of the compression spring 127 to provide full and unrestricted flow of fluid from the conduit section 123 to the conduit section 122 through the passage means 117. However, when fluid flow is from the conduit section 122 toward the conduit section 123 through the passage means 117, the compression spring 127 closes the valve member 125 against the valve seat 126 to prevent such fluid flow.

However, a second passage 128 is formed in the housing means 116 and is interconnected to the passage 117 on opposite sides of the one-way check valve means 124 thereof so as to be in fluid communication with the conduit sections 122 and 123. The passage 128 is adapted to have the flow of fluid thereto controlled by an adjusting member 129 in a manner well known in the art, the adjusting member 129 having a threaded section 130 disposed in a threaded bore 131 in the housing means 116 so that an operator can rotate the adjusting member 129 by grasping a knob end 132 thereof so as to position the adjusting member 129 in a desired flow restricting position thereof to limit the rate of fluid flow through the passage 128 and, thus, the rate of fluid flow from the conduit section 122 to the conduit section 123 through the passage 128 as the one-way valve means 124 is preventing fluid flow at the time through the passage 117 for a purpose hereinafter described.

As previously stated, the piston rod section 90 is interconnected to the belt engaging means 38 while the cylinder member 84 is interconnected to the stationary support means 36 so as the belt engaging means 38 moves downwardly in the drawings in a direction to tension the belt 21, such downward movement of the piston rod 87 and piston member 85 therewith tends to decrease the volume of the chamber section 99 while increasing the volume of the chamber section 98 a like amount. However, the fluid being displaced from the chamber section 99 by the downwardly moving piston 85 must be transferred to the chamber section 98 through the conduit means 101 and, thus, through the flow control valve means 106. Because the fluid flow through the passage 117 of the flow control means 106 is from the conduit section 123 to the conduit section 122, the one-way check valve means 124 is opened and permits such fluid flow therethrough in substantially an unrestricted manner.

Conversely, when the piston rod 87 is moved upwardly by the belt engaging means 38 being moved upwardly by the tensioned belt 21 in a manner hereinafter set forth, such upward movement of the piston rod 87 is retarded or restricted by an amount determined by the setting of the adjusting member 129 of the flow control means 106.

In particular, as the piston member 85 moves upwardly in FIG. 7, the same tends to displace fluid from the chamber section 98 to the chamber section 99 through the passage defining means 100 and thus the fluid flow through the flow control valve means 106 is from the conduit section 122 to the conduit section 123 whereby the one-way check valve means 124 closes the passage 117 so that the entire fluid flow has to pass through the restricted passage 128 of the flow control valve 106 and thereby restricts the upward movement of the belt engaging means 38 relative to the belt 21 for a purpose hereinafter described.

While the flow control valve means 106 has been previously illustrated and described as merely restricting fluid flow in one direction thereof in an adjustable manner, it is to be understood that the flow control valve means 106 can be a fixed flow control valve means, be an adjustable flow control valve means in both directions of flow therethrough and even be adapted to close the passage defining means 100 to substantially lock the idler pulley 41 in a set position relative to the support means 36 as will be apparent hereinafter.

Also, while it is presently preferred that the fluid that fills the chamber sections 98, 99 and the passage defining means 100 comprises a liquid, such as a hydraulic oil or the like, it is to be understood that any suitable fluid, such as air or other gas or gases, can be utilized and will function substantially in the same manner. Therefore, the dampening means 40 is referred to as a fluid dampening means.

In order to mount the tensioner 22 of this invention to the bracket 37 of the engine 20, the rear wall 52 of the support member 44 has an externally threaded fastening member 133 secured thereto and adapted to be received in an opening (not shown) in the bracket 37 and be secured thereto by a nut (not shown) threaded on the threaded fastening member 133 in a manner well known in the art. In order to prevent rotation of the tensioner 22 relative to the support bracket 37, one or more rigid pins 134 can be secured to the rear wall 52 of the support member 44 and be received in suitable openings (not shown) in the bracket 37 at the same time the fastening member 33 is being received in its opening. However, it is to be understood that other mounting means can be utilized to secure the tensioner 22 to the bracket 37 as desired.

Therefore, it can be seen that it is a relatively simple method of this invention to make the improved belt tensioner 22 of this invention that is adapted to operate in a manner now to be described.

When the tensioner 22 of this invention has been mounted by its support member 44 to the bracket 37 of the engine 20 in the manner previously described so that the idler pulley 41 thereof is engaging against the belt 21 under the urging force of the springs 79, the installer can adjust the adjusting members 65 upwardly or downwardly relative to the top plate 58 so that the springs 79 will be under a certain initial compression and thereby be providing a predetermined force against the belt 21 in the at rest position of the engine 20. In addition, the flow control valve 106 has been either factory adjusted or installer adjusted to set the desired differential flow characteristics between the chambers 98 and 99 of the dampening means 40.

Thereafter, each time the engine 20 is initially started so as to cause slack in the slack side 33 thereof and provide a tensioning force thereon as determined by the force of the springs 79, such inward movement of the pulley 41 causes the piston member 85 to move downwardly in FIG. 7 and displace fluid in the chamber 99 through the passage defining means 100 and the flow control valve means 106 to the chamber 98 in a manner to dampen such downward movement of the pulley 41.

Thus, it can be seen that as the belt 21 is traveling in the direction of the arrow 35 in FIGS. 1 and 2 by the running engine 20, any vibrations and oscillations of the belt 21, such as caused by the turning on and off of the air conditioning compressor 31 as previously set forth, will cause an up and down oscillation of the portion 33 of the belt 21 which movement is imposed on the pulley 41 of the tensioner 22.

In those instances where the deflection of the portion 33 of the belt 21 is upwardly in FIGS. 1 and 2 to tend to cause the pulley 41 to move upwardly relative to the support means 36, such movement causes the piston member 85 to move upwardly and thereby force the fluid from the chamber 98 through the passage defining means 100 and flow control valve 106 to the chamber 99 and since the flow control valve 106 is set to restrict such flow at a greater rate than in the reverse direction of fluid flow through the passage defining means 100, such upward movement of the pulley 41 relative to the support means 36 is at a slower rate than when the pulley 41 is being moved downwardly away from the support means 36, the flow control means 106 being such that even the downward movement of the pulley 41 away from the support means 36 is dampened to a certain degree.

In this manner, it is believed that the dampening means 40 of this invention will prolong the life of the tensioner 22 so that rapid oscillations of the springs 79 thereof cannot take place and the springs 79 will perform their tensioning function in a relatively smooth manner.

In particular, since the flow control means 106 provides a preferential flow ratio that can be controlled, the tensioner 22 will deliver increased tension on the belt 21 when the belt 21 is subjected to acceleration and/or heavy cyclic loads commonly encountered in belt drive systems. Accordingly, if the fluid flow from chamber 98 to chamber 99 is more restrictive than reverse flow, load fluctuations in the belt system will result in an increased pressure on the top side 88 of the piston 85 which will force the idler pulley 41 down into the belt 21 and result in greater belt tension. In this manner, the tensioner 22 will deliver greater tension when the system demands and less tension when less tension is required. This can result in increased bearing life in belt driven accessories, reduced belt slippage under heavy loading conditions, and an increased effective life of the tensioner 22 itself.

While one form of fluid dampening means 40 for the tensioner 22 of this invention has been illustrated and described, it is to be understood that other fluid dampening means can be utilized for the tensioner 22 of this invention, as desired.

For example, another belt tensioner of this invention is generally indicated by the reference numeral 22A in FIG. 8 and parts thereof similar to the tensioner 22 previously described are indicated by like reference numerals followed by the reference letter "A."

As illustrated in FIG. 8, the tensioner 22A is substantially identical to the tensioner 22 previously described except that the fluid dampening means 40A thereof comprises a substantially conventional shock absorber structure having a first tubular member 135 telescoped in sliding and sealing relation within an open end 136 of another tubular member 137, a closed end 138 of the tubular member 135 being secured to the plate 48A of the belt engaging means 38A while a closed end 139 of the tubular member 137 is secured to the top plate 58A of the support member 44A so as to be interconnected to the support means 36A.

In particular, the closed end 138 of the tubular member 135 is secured to the plate 48A by a fastening means 140 being disposed in the opening 113A of the plate 48A and being held thereto by the nut 114A, the fastening means 140 being secured in an opening 141 in the closed end 138 of the tubular member 135 in any suitable manner.

The closed end 139 of the tubular member 137 has a fastening means 142 carried thereby and being received in an opening 143 passing through the top wall 58A of the support means 44A and being secured thereto by a suitable nut 144.

The fastening means 142 also includes a piston-like rod 145 being suspended within an open end 146 of the tubular member 135 and carrying a piston means 147 on the lower end 148 thereof so that the piston means 147 is held stationary by the support means 44A while the tubular member 135 is adapted to slide relative to the piston means 147.

The piston means 147 divides the tubular member 135 into two chamber sections 149 and 150, the piston member 147 having a plurality of openings 151 passing therethrough to fluidly interconnect the chambers 149 and 150 together.

However, a movable valve member 152 is carried on a reduced sleeve portion 153 of the end 148 of the rod 145 so that the valve member 152 can be disposed against a lower shoulder 154 of the rod 148 and thereby be disposed away from some of the passage 151 of the piston member 147 while being adapted to move upwardly on the sleeve portion 153 to engage against the piston member 147 and close off one or more of the passages 151 in a manner and for a purpose hereinafter described.

A suitable hydraulic fluid, such as a hydraulic oil 155, is disposed in the chambers 149 and 150 and in the embodiment illustrated in FIG. 8, the chamber 150 is only filled to a level 156 in order to compensate for the amount of volume being taken up by the open end 146 of the tubular member 135 telescoping upwardly into the tubular member 137 as will be apparent hereinafter.

Therefore, it can be seen that it is a relatively simple method of this invention to make the tensioner 22A in the manner previously described in connection with the tensioner 22 and merely substitute the shock absorber means 40A for the fluid dampening means 40 thereof to operate in a manner now to be described.

After the support means 36A has been mounted to the engine bracket 37 in the manner previously described and the initial compression force of the compression springs 39A have been set in the manner previously described for the tensioner 22, any downward movement of the belt engaging means 38A under the force of the compression springs 79A causes the tubular member 135 to move downwardly relative to the tubular member 137 and thereby increase the volume of the chamber 149 so that a resulting vacuum condition in the chamber 149 immediately draws fluid from the chamber 150 through the openings 151. The openings 151 are so sized that the same provide a desired dampening to such downward movement of the belt engaging means 38A. Of course, the openings 151 can be so designed that there will be no restriction of such downward movement of the belt engaging means 38A under the force of the compression springs 79A if desired.

Conversely, when the engaged belt tends to move the belt engaging means 38A upwardly in FIG. 8, such upward movement of the tubular member 135 relative to the tubular member 137 tends to cause a decrease in the volume of the chamber 149 so that the fluid 155 therein is forced through the openings 151 into the chamber 150. However, such upward flow of the fluid 155 relative to the stationary piston 147 causes the valve member 152 to move upwardly and close off one or more of the passages 151 so that the fluid flow through the piston member 147 from the chamber 149 to the chamber 150 is restricted to thereby restrict upward movement of the belt engaging means 38A at a rate greater than when the belt engaging means 38A is moved downwardly for the reasons previously set forth in connection with the tensioner 22.

Therefore, it can be seen that the shock absorber means 40A is disposed in a parallel relation between the parallel springs 79A to render the tensioner 22A relatively small and compact in the same manner that the piston and cylinder means 84, 85 is disposed in a parallel relation to the springs 79 to render the tensioner 22 relatively small and compact, the shock absorber means 40A and piston and cylinder means 84, 85 each functioning to fluid dampen movement of the respective belt engaging means 38A and 38 relative to the respective support means 36A and 36.

Another belt tensioner of this invention is generally indicated by the reference numeral 22B in FIGS. 9-12 and parts thereof similar to the tensioners 22 and 22A previously described are indicated by like reference numerals followed by the reference letter "B."

As illustrated in FIGS. 9 and 10, the tensioner 22B is essentially the same as the tensioner 22 previously described except that the same utilizes another fluid dampening means of this invention that is generally indicated by the reference numeral 40B and comprises an outer ring-like member 157 and an inner ring-like member 158 disposed in the outer ring member 157 with the ring members 157 and 158 being arranged for relative rotational movement therebetween whereby the fluid dampening means 40B comprises a rotary dampening means.

In particular, the ring-like member 157 is substantially cylindrical with an inner peripheral cylindrical surface 159 and a rear wall 160 cooperates with a closure or front wall member 161 to define a chamber 162 within the ring-like member 157.

The inner ring-like member 158 comprises a substantially cylindrical member having an outer peripheral cylindrical surface 163 adapted to face the internal peripheral surface 159 of the outer ring member 157 and is mounted on a central shaft 164 that has one end 165 journaled in a closed ended bore 166 in the cover member 161 and another end 167 that passes through an opening 168 in the rear wall 160 of the outer ring member 157.

The rear wall 160 of the outer ring member 157 is adapted to be secured to the rear wall 52B of the support member 44B of the tensioner 22B in any suitable manner, such as by welding or the like, with the shaft 164 of the dampening means 40B passing through an opening 169 in the rear wall 52B while being rotatable therein.

The end 167 of the shaft 164 carries a pinion gear 170 that has its gear teeth 170' adapted to be disposed in meshing engagement with teeth 171 of a rack-like member 172 secured to the transverse wall 48B of the belt engaging means 38B of the tensioner 22B. For example, the rack-like member 172 can have an externally reduced rod-like part 173 passing through the opening 113B in the wall 48B to be secured thereto by the nut 114B whereby the rack-like part 172 of the fluid dampening means 40B is mounted in parallel relation between the parallel springs 79B and thereby permits the up and down movement of the wall 48B to be translated into rotary movement of the shaft 164 and, thus, rotary movement of the inner ring-like member 158 relative to the outer ring-like member 157 for a purpose hereinafter described.

The inner ring-like member 158 has a plurality of circumferentially spaced and radially outwardly extending vanes 174 having free ends 175 disposed closely adjacent the internal peripheral surface 159 of the outer ring-like member 157 for a purpose hereinafter described.

Similarly, the outer ring-like member 157 has a plurality of circumferentially spaced and radially inwardly extending vanes 176 respectively provided with free ends 177 disposed closely adjacent the outer peripheral surface 163 of the inner ring-like member 158 for a purpose hereinafter described, the vanes 176 of the outer ring-like member 157 and the vanes 174 of the inner ring-like member 158 being disposed in the staggered relation illustrated in FIG. 11 to permit limited rotary movement of the inner ring-like member 158 in both a clockwise and counter clockwise direction until the vanes 174 abut against the vanes 176 as will be apparent because the vanes 176 are disposed in the rotary path of movement of the vanes 174.

By disposing a suitable dampening fluid in the chamber 162 of the rotary dampening means 40B, such as a hydraulic oil or the like, the rotary movement of the inner ring-like member 158 relative to the outer ring-like member 157 can be controlled by the degree of spacing provided between the outer free ends 175 and 177 of the vanes 174 and 176 and the cooperating peripheral surfaces 159 and 163 of the ring-like members 157 and 158 as will be apparent hereinafter.

Also, the amount of fluid dampening in the direction of rotation of the inner ring-like member 158 relative to the outer ring-like member 157 can be preferentially controlled by changing the angle of attack of one side 178 or 179 of the vanes 174 relative to the other side 179 and 178 thereof and/or the angle of attack of one side 180 or 181 of the vanes 176 relative to the outer side 181 or 180 thereof. In addition or alternately thereto, the vanes 174 and/or vanes 176 can be provided with one-way check valves in passages passing through the opposed sides 178 and 179 thereof to permit unrestricted flow in one direction therethrough and restricted flow in the other direction therethrough as will be apparent hereinafter.

In any event, when the desired dampening fluid, such as a hydraulic oil or the like is disposed within the chamber 162, the dampener 40B will dampen up and down movement of the belt engaging means 38B of the tensioner 22B through rotary movement of the inner ring-like member 158.

Therefore, it can be seen that it is a relatively simple method of this invention to form the tensioner 22B in the manner previously described and to utilize the rotary dampener 40B of this invention therewith to operate in a manner now to be described.

After the tensioner 22B has been mounted to the mounting bracket 37 of the engine 20 and the force of the springs 79B has been set in the manner previously described for the tensioner 22, subsequent downward movement of the belt engaging means 38B under the force of the compression springs 79B in a belt tensioning direction causes the rack-like member 172 to move downwardly therewith and thereby rotate the pinion gear 170 in a counterclockwise direction in FIG. 9 to cause counterclockwise rotation of the shaft 164 and, thus, counterclockwise rotation of the inner ring-like member 148 relative to the outer ring-like member 157 in FIG. 11 whereby the inner vanes 174 tend to drive the fluid against the sides 179 thereof toward the sides 180 of the outer vanes 176 and thereby cause the hydraulic fluid in the collapsing pockets between the vanes 174 and 176 to be forced between the free ends 177 of the vanes 176 and the inner peripheral surface 163 of the inner ring-like member 58 as well as through the spacing between the free ends 175 of the inner vanes 174 and the inner peripheral surface 159 of the outer ring-like member 157 in a manner to retard or restrict such downward movement of the belt engaging means 38B for the dampening reasons previously set forth.

Conversely, when the tensioned belt tends to move the belt engaging means 38B upwardly in FIGS. 9 and 10, such upward movement of the transverse wall 48B carries the rack-like member 172 therewith and causes the pinion gear 170 to rotate in a clockwise direction in FIG. 9 and thereby cause clockwise rotation of the inner ring-like member 158 relative to the outer ring-like member 157 so that the inner vanes 174 have the sides 178 thereof tending to compress the fluid toward the sides 181 of the outer vanes 176. Thus, the fluid in the collapsing pockets of the dampener 40B is forced through the space between the inner free ends 177 of the outer vanes 176 and the inner peripheral surface 163 of the inner ring-like member 158 as well as between the outer free ends 175 of the inner vanes 174 and the inner peripheral surface 159 of the outer ring member 157 to restrict such rotary movement and thereby dampen the upward movement of the belt engaging means 38B relative to the support means 36B.

As previously set forth, by making the rotary motion of the dampener 158 more restrictive in the clockwise rotation thereof in FIG. 11 than in the counterclockwise rotation thereof, a greater restrictive force will be imposed on the belt engaging means 38B in a direction thereof away from the belt than toward the belt for the reasons previously set forth.

While the rotary dampening means 40B of this invention has been illustrated and described as being particularly adapted to provide a fluid dampening means for the tensioner 22B it is to be understood that the rotary dampener 40B of this invention can be utilized for dampening other devices than belt tensioners as desired whereby the fluid dampening device 40B of this invention is not to be limited to only a belt tensioner arrangement.

Another belt tensioner of this invention is generally indicated by the reference numeral 22C in FIGS. 13-21 and parts thereof similar to the tensioners 22, 22A and 22B previously described are indicated by like reference numerals followed by the reference letter "C."

As illustrated in FIGS. 13 and 14, it can be seen that the belt tensioner 22C is mounted to the mounting bracket 37C of the automobile engine 20C having the endless power transmission belt 21C being driven by the drive pulley 23C to drive the pulleys 24C, 25C, 26C, 27C and 30C in the manner previously described.

The belt tensioner 22C of this invention is believed to function in the same manner as the tensioner 22 previously described for tensioning the belt 21C as the tensioners 22 and 22C have basically the same structure.

In particular, the tensioner 22C comprises a support means 36C adapted to be fixed to the mounting bracket 37C of the engine 20 as illustrated in FIGS. 13 and 14. The tensioner 22C has a belt engaging means that is generally indicated by the reference numeral 38C and is movably carried by the support means 36C in a manner hereinafter set forth. The tensioner 22C has mechanical spring means that is generally indicated by the reference numeral 39C operatively associated with the support means 36C and belt engaging means 38C to tend to urge the belt engaging means 38C against the slack side 33C of the belt 21C in substantially a true vertically downwardly direction in a manner to substantially bisect the angle made by the belt 21C between the pulleys 27C and 30C as illustrated in FIGS. 13 and 14.

The belt tensioner 22C also includes a fluid dampening means that is generally indicated by the reference numeral 40C and is operatively associated with the support means 36C and the belt engaging means 38C to dampen movement of the belt engaging means 38C relative to the support means 36C in substantially the same manner as the dampening means 40 previously described.

Therefore, it can be seen that the tensioner 22C is generally identical to the tensioner 22 previously described but has unique features not found in the tensioner 22 as will be apparent hereinafter.

For example, the belt engaging means 38C and the support means 36C of the tensioner 22C have a tongue and groove means that is generally indicated by the reference numeral 200 for providing the sliding movement therebetween.

In particular, the tongue and groove means 200 comprises a substantially flat plate-like tongue 201 of the support means 36C being telescopically disposed within a cooperating groove 202 of the belt engaging means 38C in a manner now to be described.

The belt engaging means 38C comprises a one-piece metal member formed to define a flat base 203 having a pair of spaced parallel side flanges 204 and 205 depending from opposed sides 206 and 207 of the base member 203 and rotatably supporting a conventional belt engaging pulley 208 therebetween and beneath the base member 203. As illustrated in FIG. 21, the side flanges 204 and 205 of the base member 203 have openings 209 passing therethrough and receiving a pivot shaft 210 that rotatably mounts the pulley 208 therebetween in a manner well known in the art.

The side flange 205 has a pair of opposed ends 211 respectively folded backwardly in a U-shaped manner as illustrated in FIG. 17 to define the groove 202 with the side flange 205 which receives the plate-like tongue 201 of the support means 36C therein to guide sliding movement of the belt engaging means 38C relative to the support means 36C as will be apparent hereinafter.

The support means 36C comprises a flat metal base plate 212 of substantially rectangular form as illustrated in FIG. 21 and having the substantially rectangular tongue-like plate 201 formed integrally therewith and extending therefrom while being of a narrower and thinner rectangular configuration than the base plate 212.

The base plate 212 carries the mounting stub 133C for mounting the tensioner 22C to the support bracket 37C of the engine 20C in the manner previously described for the stud 133 of the tensioner 22, the base plate 212 carrying the locating pin 134C for being received in a suitable opening in the support plate 37C of the engine 20C to prevent rotational movement of the support means 36C when the same is secured thereto by the mounting stud 133C.

A first L-shaped metal bracket 213 is secured to the front side 214 of the base plate 212 in any suitable manner and has an opening 215 for receiving a rod-like extension 216 on a cylinder means 217 of the fluid dampening means 40C constructed in a manner hereinafter set forth. The projection 216 of the cylinder means 217 can be fastened in the opening 215 of the bracket 213 in any suitable manner.

For example, the rod-like extension 216 can have an annular groove 218, FIG. 20, that will extend just beyond the bracket 213 and receive a C-clip therein in a manner well known in the art to prevent the projection 216 from being pulled out of the opening 215 after the same has been fully projected therethrough and received such C-clamp in a manner well known in the art.

Another L-shaped metal bracket 219 is secured to the side 214 of the support plate 212 in any suitable manner and has a cutout 220 for receiving the cylinder member 217 of the fluid dampening means 40C therein to assist in supporting the fluid dampening means 40C in the tensioner 22C as will be described hereinafter.

The bracket 219 has a pair of openings 221 passing therethrough for respectively receiving reduced cylindrical projections 222 on enlarged heads 223 of threaded adjusting members 224 respectively having threaded cylindrical nuts or retainers 225 thereon, each projection 222 having an opening 226 therein for receiving a suitable tool for rotating the respective threaded adjusting member 224 and thereby causing axial up and down movement of the retainer 225 thereon for a purpose hereinafter described.

A metal guide member 227 is fastened to the support plate 212 of the support means 36C in any suitable manner, such as by threaded fastening members 228 respectively passing through threaded openings 229 in the support plate 212 and threaded openings 230 in the guide member 227. The guide member 227 has an arcuate supporting surface 231 to engage against a cylindrical cap means 232 of the cylinder member 217 to assist in supporting the fluid dampening means 40C in the tensioner 22C as will be apparent hereinafter.

The fluid dampening means 40C has a piston rod 233 that is externally threaded for being threaded into a threaded opening 234 of the base plate 203 of the belt engaging means 38C to fasten the piston 233 thereto while, in effect, the cylinder member 217 of the fluid dampening means 40C is fastened to the support means 36C of the tensioner 22C by the aforementioned C-clip on one side of the bracket 213 and the enlarged engaging part 235 of the cylinder member 217 being disposed on the other side of the bracket 213.

The spring means 39C comprise a pair of coiled compression springs 79C respectively having their upper ends 80C bearing against the retainers 225 and their lower ends 81C bearing against button shaped spring retainers 236 carried by the base plate 203 of the belt engaging means 38C, the button retainers 236 having cylindrical projections 237 for being received in the lower coils of the springs 79C to prevent the same from slipping off of the belt engaging means 38C once assembled thereto.

In this manner, it can be seen that by rotating the threaded members 224, the spring retainers 225 can be moved axially upwardly and downwardly thereon and thereby decrease or increase the compressive force of the springs 79C tending to urge the belt engaging means 38C downwardly relative to the support means 36C in the same manner as the springs 79 of the tensioner 22 previously described.

Thus, it can be seen that it is a relatively simple method of this invention for making the tensioner 22C so as to have the spring means 79C act in a direction to tend to move the belt engaging means 38C toward the belt 21C away from the support means 36C to provide tension for the belt 21C in the manner previously described, the up and down oscillating movement of the belt 21C and, thus, of the belt engaging means 38C being dampened by fluid dampening means 40C in substantially the same manner as the dampening means 40 previously described.

However, the dampening means 40C of this invention has unique features not found in the dampening means 40 previously described.

For example, as illustrated in FIG. 20, the cylinder member 217 comprises a one-piece elongated cup-shaped member having a closed end 238 and an open end 239, the elongated cup-shaped member 217 being formed by impact extruding a slug of aluminum containing material in much the manner that the aluminum industry impact extrudes from a hockey puck-like metallic slug an elongated cup-shaped aluminum can that has an integral closed end and an open end that is subsequently closed by an end closure.

Thus, it can be seen that in the impact extruding of the metallic slug, the closed end 238 of the member 217 can be shaped to form the surface 235 and projection 216 as well as the substantially cylindrical side wall means 240 that can be subsequently externally threaded at 241 to threadedly receive the end cap means 232 thereon that has internal threads 242 as illustrated. In this manner, the cap means 232 can seal close the open end 239 of the cylinder member 217 to form the fluid dampening means 40C.

However, if desired, the end cap means 232 can be formed in the manner illustrated in FIG. 22 wherein a plug-like end cap means 243 has a cylindrical outer peripheral surface 244 provided with an annular groove 245 into which the unthreaded free end 239 of the cylindrical side wall means 240 of the cup-shaped member 217 is turned to hold the members 217 and 243 together, the peripheral side wall means 244 of the end plug means 243 having another annular groove 246 therein receiving a sealing resilient O-ring member 247 that seals against the side wall means 240 of the cup-shaped member 217 to seal the end cap means 243 and member 217 together.

As illustrated in FIG. 20, the end cap means 232 has an opening 248 passing therethrough and through which the piston rod 233 projects.

The piston means 233 includes an enlarged cylindrical portion 249 disposed within the cylinder member 217 and having an outer cylindrical periphery 250 disposed in sliding and sealing engagement with the internal cylindrical peripheral side wall means 251 of the cylinder member 217 by means of an O-ring sealing member 252 and conventional piston rings 253 as illustrated.

An insert 257 is disposed in the member 217 and is shaped to cooperate therewith to define a chamber 254 adjacent the closed end 238 of the member 217, the piston rod 233 having an upper end 255 passing through a central opening 256 in the insert 257 to be received in the chamber 255 and be sealed for sliding movement in the opening 256 of the insert 257 by an annular sealing member 258 as illustrated.

While the insert 254 can be formed of any suitable material, the same can be an injection-molded plastic part to reduce the cost of the dampener 40C.

In this manner, the enlarged portion 249 of the piston rod 233 defines two chambers 259 and 260 in the cylinder member 217 on opposite sides thereof with the chamber 259 being defined between the insert 257 and the side 261 of the piston enlargement 249 while the chamber 260 is disposed between the end cap means 232 and the side 262 of the piston enlargement 249, the chambers 259 and 260 having the same effective diameter as the upper 255 and lower portions 233 of the piston means 233 have the same diameter.

The chambers 259 and 260 are respectfully filled with fluid 263, such as a hydraulic oil or the like, to provide dampening movement of the piston portion 249 relative to the stationary cylinder member 217 for the reasons previously set forth in connection with the fluid dampening means 40 of the tensioner 22 and, in particular, in connection with the fluid dampening means 40A of FIG. 8.

In order to provide for such dampening effect, the piston portion 249 is provided with a plurality of restrictive passages 264 that extend between the opposed surfaces 261 and 262 and which control the amount of fluid that can be displaced between the chambers 259 and 260 so as to provide a retarding force to the movement of the piston rod 233 relative to the cylinder 217 as caused by the belt engaging means 38C being oscillated by the belt 21C for the reasons previously set forth.

If desired, the piston means 249 can provide a preferential control of its dampening movement by having an enlarged passage 265 provided therethrough and in which a one-way check valve means 266 is disposed so that the check valve means 266 will open when the piston rod 233 in FIG. 20 moves downwardly in the drawings to provide less of a retarding force to the downward movement of the piston rod 233 in contrast to the upward movement of the piston rod 233 wherein the check valve means 266 closes the passage 265 and thereby requires all of the fluid displaced to be through the restricted passages 264 for the reasons previously set forth. Because the upper 256 and lower 233 portions of the piston means 233 completely extend through the respective chambers 259 and 260 in all operating positions of the piston portion 249 in the cylinder member 217, the piston rod 233 does not displace more fluid in one chamber 259 or 260 than in the other chamber 260 or 259 and therefore does not effect the operation thereof.

Therefore, it can be seen that the fluid dampening means 40C of this invention can be made by the method of this invention previously described to provide fluid dampening of the operating movement of the belt engaging means 38C of the tensioner 22C relative to its support means 36C for the reasons previously set forth, the dampening means 40C being believed to be a relatively inexpensive, small and durable shock absorber type of dampening means.

However, it is to be understood that the fluid dampening means 40C can be utilized with the other tensioners 22, 22A and 22B if desired.

Therefore, since the operation of the tensioner 22C is substantially identical to the operation of the tensioners 22 and 22A previously described, the operation of the tensioner 22C need not now be set forth.

Accordingly, it can be seen that this invention not only provides improved belt tensioners, but also this invention provides improved methods for making such belt tensioners.

While the forms and methods of this invention now preferred have been illustrated and described as required by the Patent Statute, it is to be understood that other forms and method steps can be utilized and still fall within the scope of the appended claims. 

What is claimed is:
 1. In a tensioner for a power transmission belt that is adapted to be operated in an endless path, said tensioner comprising a support means for being fixed relative to said belt, a belt engaging means carried by said support means and being movable relative thereto, mechanical spring means operatively associated with said support means and said belt engaging means for urging said belt engaging means relative to said support means and against said belt with a force to tension said belt, and fluid dampening means operatively associated with said support means and said belt engaging means to dampen the movement of said belt engaging means relative to said support means in at least one direction of movement thereof, said fluid dampening means comprising a piston and cylinder means, the improvement wherein said mechanical spring means comprises a pair of coiled compression springs with their longitudinal axes disposed in substantially parallel side-by-side spaced relation, said fluid dampening means being generally disposed between said springs and in substantially parallel relation therewith, said belt engaging means and said support means having a tongue and groove means for providing for sliding movement therebetween.
 2. A tensioner as set forth in claim 1 wherein said piston and cylinder means comprises a cylinder member and a piston member disposed in said cylinder member, one of said members being operatively interconnected to said support means and the other of said members being operatively interconnected to said belt engaging means whereby said members are arranged for relative movement therebetween.
 3. A tensioner as set forth in claim 1 wherein said tongue and groove means comprises means defining said groove on said belt engaging means and means defining said tongue on said support means.
 4. A tensioner as set forth in claim 3 wherein said belt engaging means comprises a base member having a pair of spaced apart side flanges extending therefrom and a pulley rotatably secured to and between said side flanges, one of said side flanges having said means defining said groove on the side thereof opposite to the side thereof that is adjacent to said pulley.
 5. A tensioner as set forth in claim 4 wherein said base member and said side flanges comprise a one-piece member.
 6. A tensioner as set forth in claim 4 wherein each said spring has one end thereof bearing against said base member of said belt engaging means and has another end thereof bearing against said support means.
 7. A tensioner as set forth in claim 6 wherein said support means has a pair of adjustable parts against which said other ends of said springs respectively bear whereby the urging force of said springs is adjustable.
 8. In a tensioner for a power transmission belt that is adapted to be operated in an endless path, said tensioner comprising a support means for being fixed relative to said belt, a belt engaging means carried by said support means and being movable relative thereto, mechanical spring means operatively associated with said support means and said belt engaging means for urging said belt engaging means relative to said support means and against said belt with a force to tension said belt, and fluid dampening means operatively associated with said support means and said belt engaging means to dampen the movement of said belt engaging means relative to said support means in at least one direction of movement thereof, the improvement wherein said mechanical spring means comprises a pair of springs disposed in substantially parallel spaced relation, said fluid dampening means having at least a part thereof disposed between said springs and in substantially parallel relation therewith, said belt engaging means and said support means having a tongue and groove means for providing for sliding movement therebetween, said fluid dampening means comprising a piston and cylinder means, said piston and cylinder means comprising a cylinder member and a piston member disposed in said cylinder member, one of said members being operatively interconnected to said support means and the other of said members being operatively interconnected to said belt engaging means whereby said members are arranged for relative movement therebetween, said cylinder member comprising a one-piece elongated cup-shaped member having a closed end and an open end, said cylinder member further comprising a cap means closing said open end of said elongated cup-shaped member and having an opening therethrough, said piston member having a piston rod projecting through said opening of said cap means.
 9. A tensioner as set forth in claim 8 wherein said cap means has thread means, said open end of said elongated cup-shaped member having thread means threaded to said thread means of said cap means to secure said cap means and said elongated cup-shaped member together.
 10. A tensioner as set forth in claim 8 wherein said cap means has an annular groove means, said open end of said elongated cup-shaped member being turned into said annular groove means of said cap means to secure said cap means and said elongated cup-shaped member together.
 11. A tensioner as set forth in claim 4 wherein said elongated cup-shaped member is formed of aluminum containing material.
 12. In a tensioner for a power transmission belt that is adapted to be operated in an endless path, said tensioner comprising a support means for being fixed relative to said belt, a belt engaging means carried by said support means and being movable relative thereto, mechanical spring means operatively associated with said support means and said belt engaging means for urging said belt engaging means relative to said support means and against said belt with a force to tension said belt, and fluid dampening means operatively associated with said support means and said belt engaging means to dampen the movement of said belt engaging means relative to said support means in at least one direction of movement thereof, the improvement wherein said mechanical spring means comprises a pair of springs disposed in substantially parallel spaced relation, said fluid dampening means having at least a part thereof disposed between said springs and in substantially parallel relation therewith, said belt engaging means and said support means having a tongue and groove means for providing for sliding movement therebetween, said tongue and groove means comprising means defining said groove on said belt engaging means and means defining said tongue on said support means.
 13. A tensioner as set forth in claim 12 wherein said belt engaging means comprises a base member having a pair of spaced apart side flanges extending therefrom and a pulley rotatably secured to and between said side flanges, one of said side flanges having said means defining said groove on the side thereof opposite to the side thereof that is adjacent to said pulley.
 14. A tensioner as set forth in claim 13 wherein said base member and said side flanges comprise a one-piece member.
 15. A tensioner as set forth in claim 13 wherein said springs comprise coiled compression springs, each said spring having one end bearing against said base member of said belt engaging means and having another end bearing against said support means.
 16. A tensioner as set forth in claim 15 wherein said support means has a pair of adjustable parts against which said other ends of said springs respectively bear whereby the urging force of said springs is adjustable.
 17. In a tensioner for a power transmission belt that is adapted to be operated in an endless path, said tensioner comprising a support means for being fixed relative to said belt, a belt engaging means carried by said support means and being movable relative thereto, mechanical spring means operatively associated with said support means and said belt engaging means for urging said belt engaging means relative to said support means and against said belt with a force to tension said belt, and fluid dampening means operatively associated with said support means and said belt engaging means to dampen the movement of said belt engaging means relative to said support means in at least one direction of movement thereof, the improvement wherein said mechanical spring means comprises a pair of springs disposed in substantially parallel spaced relation, said fluid dampening means having at least a part thereof disposed between said springs and in substantially parallel relation therewith, said fluid dampening means comprising a piston and cylinder means, said piston and cylinder means comprising a cylinder member and a piston member disposed in said cylinder member, one of said members being operatively interconnected to said support means and the other of said members being operatively interconnected to said belt engaging means whereby said members are arranged for relative movement therebetween, said cylinder member comprising a one-piece elongated cup-shaped member having a closed end and an open end, said cylinder member further comprising a cap means closing said open end of said elongated cup-shaped member and having an opening therethrough, said piston member having a piston rod projecting through said opening of said cap means.
 18. A tensioner as set forth in claim 17 wherein said cap means has thread means, said open end of said elongated cup-shaped member having thread means threaded to said thread means of said cap means to secure said cap means and said elongated cup-shaped member together.
 19. A tensioner as set forth in claim 17 wherein said cap means has an annular groove means, said open end of said elongated cup-shaped member being turned into said annular groove means of said cap means to secure said cap means and said elongated cup-shaped member together.
 20. A tensioner as set forth in claim 17 wherein said elongated cup-shaped member is formed of aluminum containing material. 